US20130334887A1 - Multi-terminal dc transmission system and method and means for control there-of - Google Patents
Multi-terminal dc transmission system and method and means for control there-of Download PDFInfo
- Publication number
- US20130334887A1 US20130334887A1 US13/807,650 US201013807650A US2013334887A1 US 20130334887 A1 US20130334887 A1 US 20130334887A1 US 201013807650 A US201013807650 A US 201013807650A US 2013334887 A1 US2013334887 A1 US 2013334887A1
- Authority
- US
- United States
- Prior art keywords
- control
- power
- converter station
- transmission system
- converter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J1/00—Circuit arrangements for dc mains or dc distribution networks
- H02J1/10—Parallel operation of dc sources
- H02J1/12—Parallel operation of dc generators with converters, e.g. with mercury-arc rectifier
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/36—Arrangements for transfer of electric power between ac networks via a high-tension dc link
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/66—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal
- H02M7/68—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters
- H02M7/72—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/75—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means
- H02M7/757—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only
- H02M7/7575—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output with possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a thyratron or thyristor type requiring extinguishing means using semiconductor devices only for high voltage direct transmission link
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/60—Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]
Definitions
- the invention relates generally to the field of power transmission systems, and in particular to a multi-terminal DC power transmission system and to control thereof.
- HVDC High Voltage Direct Current
- AC alternating current
- HVDC power transmission has been point-to-point two terminal power transmission with a few exceptions.
- a multi-terminal HVDC power transmission is more complex than the ordinary point-to-point power transmission.
- the control system is more elaborate and telecommunication requirements between stations become larger.
- a major reason for the more elaborate control system is difficulties to control the power flow within a large HVDC system, especially at disturbances.
- control actions In case of disturbances within the HVDC power transmission network, for example outages of converters or lines, control actions have to be taken in order to ensure stability of the network and the power distribution.
- the aim of any such control actions is to handle the disturbances and provide a distribution of load that is acceptable and that enables uninterrupted power to be delivered to end users.
- Droop control is a well known method for handling disturbances.
- Such droop control is described in, for example, “Control of Multiterminal HVDC Transmission for Offshore Wind Energy”, T. Haileselassie et al.
- the document is mainly aimed at means for avoiding the need for communication when controlling the power distribution at a disturbance.
- a drawback of the described droop control method is difficulties handling minor disturbances. In particular, even a rather small error in measurement will give great impact on the whole system.
- a method for controlling power flow in a multi-terminal DC power transmission system comprises the first step of controlling the power flow to a steady state reference operating point for operating points within a control dead band defined for each respective converter station.
- the method further comprises the second step of controlling the power flow by means of droop control in at least one of the converter stations upon detection of exceeding of an end point of one or more of the control dead bands.
- the invention thus provides a reliable and adaptable multi-terminal DC power transmission system.
- the multi-terminal DC power transmission system in accordance with the invention can be utilized for any type of network configuration, including complex network configurations.
- the solution is thus suitable for all types of network configurations and this in turn provides a high flexibility when deciding converter station locations.
- dead band in combination with droop control, there is no need for a common voltage reference during minor disturbances and mentioned problems of the prior art is overcome and any type of network configuration can be handled.
- the steady state reference operating points are related to a voltage profile of steady state operation of the multi-terminal DC transmission system and the control dead band are defined as steady state operation.
- the droop characteristics for the droop control are defined individually for each converter station. Further, a particular converter station may have several different droop constants. The droop characteristics of the converter stations are one part for determining power sharing within the multi-terminal DC transmission system and the DC voltage at disturbances.
- each converter station is provided with limitations in power/current and overvoltages. Having break points in the droop characteristics ensures that the capability of any converter station or the capability of its connected AC network is not exceeded.
- the steady state reference operating point is determined by a master control unit of the multi-terminal DC power transmission system in consideration of DC voltage profile of the entire multi-terminal DC power transmission system. Transient and dynamic stability is ensured and the risks for interaction between power controls of different converter stations are thereby minimized.
- the invention also relates to a corresponding multi-terminal DC power transmission system, whereby advantages similar to the above are achieved.
- FIG. 1 illustrates an embodiment of a multi-terminal DC power transmission system in accordance with the present invention.
- FIG. 2 illustrates exemplary converter station characteristics
- FIG. 3 illustrates a flow chart over steps included in a method in accordance with an embodiment of the invention.
- a multi-terminal DC power transmission system is conventionally understood to comprise a DC power transmission system comprising more than two converter stations.
- the invention is described in connection with the multi-terminal DC transmission system, it is realized that the present invention is also applicable to a DC transmission system comprising only two converter stations.
- the multi-terminal DC power transmission system is preferably a HVDC system, wherein HV may be defined to comprise any voltage level ranging for example from 300 kV, or even 80 kV. However, it is realized that the present invention is not restricted to any particular voltage levels or current levels, but is applicable to any such levels. Power transmission is understood to comprise transmission of electric power.
- FIG. 1 illustrates an embodiment of a multi-terminal DC power transmission system 1 in accordance with the invention, in the following denoted DC transmission system in order of simplicity.
- the DC transmission system 1 comprises a number of converter stations 10 A, 10 B, 10 C, 10 E and 10 E. Although five converter stations are illustrated in the FIG. 1 , it is realized that any number of converter stations can be included.
- the converter stations 10 A, . . . , 10 E in turn comprise inverters converting DC to AC, and/or rectifiers converting AC to DC.
- Other components and means conventionally used within a power network for enabling DC power transmission, but not forming part of the present invention, may also be included in the converter stations 10 A, . . . , 10 E.
- the converter station 10 A, . . . , 10 E comprises an AC side 11 A, 11 B, 11 C, 11 D and 11 E, connectable to an AC network 13 A, 13 B, 13 C, 13 D and 13 E.
- the converter stations 10 A, . . . , 10 E further comprises a DC side 12 A, 12 B, 12 C, 12 D and 12 E connectable to the DC transmission system 1 for power transmission.
- the converter stations 10 A, . . . , 10 E may be interconnected in any suitable manner, thereby constituting the DC transmission system 1 .
- Each converter station 10 A, . . . , 10 E thus have an AC side 11 A, . . . , 11 E and a DC side 12 A, . . . , 12 E.
- the converter stations 10 A, . . . , 10 E may be interconnected by means of power transmission lines, also denoted cable lines, or by overhead lines in a known manner. Such power transmission lines allows the power transmission and are illustrated in the FIG. 1 by reference numerals 14 A, 14 B, 14 C, 14 D, 14 E and 14 F.
- the DC transmission system 1 further comprises a master control unit 16 responsible for coordination between the converter stations 10 A, . . . , 10 E. More specifically, the master control unit 16 , also denoted grid master control, is arranged to coordinate the operation of the entire DC transmission system 1 , and especially at disturbances and reconfigurations. These functions, as well as other control functions not mentioned, e.g. conventional control functions, may be implemented in software, hardware and/or firmware.
- the master control unit 16 may for example be a general purpose computer comprising appropriate software instructions enabling the desired control functions, for example able to send operating instructions to the converter stations.
- Examples of such control functions comprise receiving updated information regarding loading of all converter stations and especially the loading of a converter station pre-selected for DC voltage control; loading of all cable lines; DC voltages in all converter stations; limitations regarding voltage and current; desired dispatch for each converter station.
- the master control unit 16 may be located in one of the converter stations or located elsewhere in the DC transmission system 1 .
- the master control unit 16 is the main tool for proper restoration of the operation after faults and disturbances
- the DC transmission system 1 is nevertheless designed so as to function even in case of failure thereof and/or in case of slow response from the master control unit 16 .
- Each converter station comprises a local control unit as well, for example enabling power regulation in the converter station.
- a sub-grid of the entire grid i.e. the DC transmission system 1
- the master control unit 16 then coordinates the area master controls for each area.
- the converter stations 10 A, . . . , 10 E are preferably connected to a communication network 15 , whereby data can be exchanged between the converter stations and whereby the master control unit 16 is able to communicate with each converter station 10 A, . . . , 10 E.
- the communication network 15 may for example be a telecommunication network or a wide area network such as the Internet or any combination of communication networks.
- the type of control of the DC transmission system 1 is dependent on the prevailing conditions therein; during steady state and minor disturbances the converter stations 10 A, . . . 10 E are arranged to work within a respective pre-defined dead band, while during large disturbances a droop control function is used.
- Minor disturbances comprise for example normal load variations within the DC transmission system 1 .
- one of the converter stations 10 A, . . . , 10 E of the DC transmission system 1 is arranged to be DC voltage controlled, striving to keep its DC voltage U DC constant.
- the DC voltage controlled converter station controls the DC voltage in such a way that all (or some) of the converter stations can take their part of the disturbance.
- the remaining converter stations are arranged to be power controlled, striving to keep their power P constant.
- DC transmission system 1 only one converter station is in DC voltage control, which converter station may be pre-selected for DC voltage control.
- the other converter stations are pre-selected for power control, or are else in islanded network operation.
- a converter station in islanded network operation is disconnected from the DC transmission system 1 and is controlling both the frequency and the AC voltage, that is, the master control is not controlling the converter station.
- the converter station that is pre-selected for DC voltage control always operates in DC voltage control. This is in contrast to the converter stations pre-selected for power control, which operates in DC voltage control when disconnected from the DC transmission system 1 . When the converter station pre-selected for power control is re-connected to the DC transmission system 1 , it is transferred to power control.
- the converter station to be in DC voltage control may be suitably chosen, for example a converter station centrally located within the DC transmission system 1 and/or being connected to a relatively stable and strong ac-network.
- the connected ac network of the chosen converter station should have the capability to temporarily take the balance power variation due to load variations in converter stations operating in islanded network operation, in frequency control, in power oscillation damping etc.
- the chosen converter station should be close to the electrical central point and the DC voltage should be close to the median DC voltage of the DC transmission system 1 .
- the choice of converter station in DC voltage control may be selected in any other suitable way.
- Each converter station in power control controls its AC side power to a reference value, a steady state reference operating point, provided that the dc-voltage is within acceptable limits.
- the limits of a converter station are described more in detail later. Only converter stations in normal power control can control their power and the converter station in DC voltage control has to take the balance.
- the power of converter stations in power control can be controlled in any suitable manner, for example by means of conventional PI regulation, performed by the local control unit.
- a converter station set in power control mode may be placed on equality with current control mode, as the power is nearly linear with the current.
- the DC voltage in a central point of the system is fixed in a short term. Otherwise, power changes in any converter station will result in voltage variation in all other converter stations, which is to be counteracted by the power control in those converter stations.
- the set point for the DC voltage reference for the converter station in DC voltage control is defined by the master control unit 16 , set in view of the DC voltage profile of the complete DC transmission system 1 .
- the converter station pre-selected for DC voltage control controls its voltage to the above short-term fixed reference within a defined power range for normal operation, i.e. within a control dead band for the voltage controlled converter station.
- the remaining converter stations i.e. the converter stations pre-selected for power control, control their ac side power to the desired order value as long as the DC voltage is within a defined voltage range for normal operation, i.e. within a control dead band for the power controlled converter stations.
- the converter station has a voltage/power droop characteristic, which is described more in detail later in the description.
- the normal steady state operation also includes minor disturbances, for example normal load variations of the DC transmission network 1 .
- the power, current and voltage limits of a converter station are normally defined by local conditions. Such local conditions are communicated to the master control unit 16 from each converter station 10 A, 10 B, 10 C, 10 D, 10 E. Based on DC transmission system 1 dispatch, the DC voltage profile of the system and known restrictions and limitations, the master control unit 16 defines a number of settings:
- FIG. 2 an example of characteristics 20 A, 20 B, 20 C, 20 D and 20 E for the five converter stations 10 A, . . . , 10 E, respectively, connected to the DC transmission system 1 is illustrated.
- a dead band is defined in accordance with the above described.
- the dead bands are indicated in the FIG. 2 at reference numerals 21 A, 21 B, 21 C, 21 D and 21 E for the respective converter stations 10 A, 10 B, 10 C, 10 D and 10 E.
- the small squares indicate the steady state operating points 22 A, 22 B, 22 C, 22 D, 22 E of the respective converter stations.
- Each respective steady state operating point 22 A, 22 B, 22 C, 22 D, 22 E is related to the local DC voltage at the respective converter station during steady state operation.
- the steady state operating points 22 A, 22 B, 22 C, 22 D, 22 E are strongly correlated.
- the difference in voltage is the voltage drops of the cables in the DC transmission system 1 .
- Converter station 10 B is pre-selected for DC voltage control while the other converter stations 10 A, 10 C, 10 D and 10 E operate in power control.
- the converter station controls its voltage or power to the short-term fixed reference.
- the converter station 10 B pre-selected for voltage control controls its voltage to the short-term fixed reference within its dead band 21 A.
- the converter station 10 B has a power dead band 21 A, within which the power is allowed to vary and still be considered to be within normal operation.
- the converter stations 10 A, 10 C, 10 D, 10 E that are in power control have voltage dead bands 21 A, 21 C, 21 D and 21 E, respectively, within which the voltage is allowed to vary and still be considered to be within normal operation.
- the sloping part of the characteristics of FIG. 2 illustrates droop characteristics of the converter stations. It is noted that a converter station may have one or several different droop characteristics. It can be seen from the FIG. 2 , that converter station 10 A, for example, has three different droop constants, while converter station 10 B has two different droop constants and converter station 10 C has a single droop constant.
- the converter station 10 B that is pre-selected for DC voltage control, will take the power imbalance within its dead band 21 B in power.
- the combined characteristics for converter station 10 B shown in FIG. 2 prevents that the converter station in DC voltage control is overloaded.
- the converter station control will prevent that the inverter is overloaded. It is the duty of the master control unit 16 to define the parameters of the converter station characteristics in such a way that the DC voltage is kept within the desired and set range even at equipment outages and other types of disturbances.
- the master control unit 16 may order more stringent limitations than the limitations set based on local conditions.
- the converter station characteristics i.e. the dead bands, the droop constants, and sometimes even the converter station limits, may have to be adapted to some degree.
- the characteristics may for example have to be adapted to the actual power flow of the DC transmission system 1 .
- the parameters of the converter station characteristics has to be recalculated by the master control unit 16 and transmitted to the converter stations 10 A, 10 B, 10 C, 10 D, 10 D.
- FIG. 2 thus illustrates the inventive idea of dead band droop control of DC voltage versus power for five converter stations 10 A, . . . , 10 E connected to the DC transmission system 1 .
- droop control is activated.
- the control of at least that particular converter station is changed to droop control. That is, if the operating point falls outside the end points of the dead band, then droop control is activated.
- any conventional droop control method may be used.
- one droop control method is to operate all converter stations in the DC transmission system in DC voltage control with a voltage reference that is dependent on the power level, that is
- the characteristic is a constant DC voltage in series with a resistance and it is stable and works well for taking care of power variations as well as an outage.
- the feedback signal is common to all of the converter stations and based on an overall voltage level in the DC transmission power network.
- the common feedback signal results in a highly improved reference tracking of set-points; it can be shown that each converter station tracks its power reference perfectly.
- An accurate load sharing in the DC grid during disturbances is accomplished and also accurate steady-state operation.
- the present invention may utilize such power flow control method.
- FIG. 3 illustrates a flow chart over steps of a method in accordance with the invention for controlling power flow within the multi-terminal DC power transmission system 1 comprising two or more converter stations 10 A, 10 B, 10 C, 10 D, 10 E.
- the method 30 comprises the first step of controlling 31 the power flow to a steady state reference operating point 22 A, 22 B, 22 C, 22 D, 22 E for operating points that lie within a control dead band 21 A, 21 B, 21 C, 21 D, 21 E defined for each respective converter station 10 A, 10 B, 10 C, 10 D, 10 E.
- the converter stations strive to keep their voltage/power at their respective steady state reference operating point.
- the control dead band comprises the earlier described power/voltage dead bands. That is, a power dead band for a voltage controlled converter station and a voltage dead band for a power controlled converter station.
- the method 30 comprises the second step of controlling 32 the power flow by means of droop control in at least one of the converter stations 10 A, 10 B, 10 C, 10 D, 10 E upon detection of exceeding of an end point of one or more of the control dead bands 21 A, 21 B, 21 C, 21 D, 21 E. That is, when an end point of the control dead band for a converter station is exceeded, then the control mode is changed to droop control from the normal steady state control.
- the end points of the control dead bands are typically exceeded in case of a failure somewhere in the DC transmission system 1 .
- the steady state reference operating point 22 A, 22 B, 22 C, 22 D, 22 E preferably comprises a voltage reference related to a voltage profile determined for steady state operation of the multi-terminal DC transmission system 1 .
- the control dead bands 21 A, 21 B, 21 C, 21 D, 21 E could be considered as steady state operation, and the steady state operation typically comprises power flow during normal operating conditions including minor load changes.
- the steady state reference operating point 22 A, 22 B, 22 C, 22 D, 22 E is preferably determined by the master control unit 16 in consideration of DC voltage profile of the entire multi-terminal DC power transmission system 1 .
- control dead bands 21 A, 21 B, 21 C, 21 D, 21 E are chosen so as to enable control of power flow within the control dead bands during steady state operation and including minor load changes within the multi-terminal DC power transmission system 1 .
- the control dead bands are also preferably chosen individually for each converter station 10 A, 10 B, 10 C, 10 D, 10 E based on requirements of each converter station.
- control dead band of a converter station 10 A, 10 B, 10 C, 10 D, 10 E comprises a power dead band or a voltage dead band.
- one of the converter stations 10 B has a power dead band 21 B, while the remaining converter stations 10 A, 10 C, 10 D, 10 E have voltage dead bands 21 A, 21 C, 21 D, 21 E.
- the droop characteristics for the droop control are defined individually for each converter station 10 A, 10 B, 10 C, 10 D, 10 E.
- limitations in power/current and overvoltages are defined for each converter station 10 A, 10 B, 10 C, 10 D, 10 E. thereby it is ensured that the capability of any converter station or the capability of its connected AC network is not exceeded.
- the invention also encompasses the multi-terminal DC power transmission system 1 comprising two or more converter stations 10 A, 10 B, 10 C, 10 D, 10 E, and means 16 for controlling power flow to a steady state reference operating point 22 A, 22 B, 22 C, 22 D, 22 E for operating points within the control dead band 21 A, 21 B, 21 C, 21 D, 21 E defined for each respective converter station 10 A, 10 B, 10 C, 10 D, 10 E.
- a steady state reference operating point 22 A, 22 B, 22 C, 22 D, 22 E for operating points within the control dead band 21 A, 21 B, 21 C, 21 D, 21 E defined for each respective converter station 10 A, 10 B, 10 C, 10 D, 10 E.
- the multi-terminal DC power transmission system 1 further comprises means 18 for controlling the power flow by means of droop control in at least one of the converter stations 10 A, 10 B, 10 C, 10 D, 10 E upon detection of exceeding of an end point of one or more of the control dead bands 21 A, 21 B, 21 C, 21 D, 21 E.
- means 19 is also provided for controlling the power flow by means of droop control in at least one of the converter stations 10 A, 10 B, 10 C, 10 D, 10 E upon detection of exceeding of an end point of one or more of the control dead bands 21 A, 21 B, 21 C, 21 D, 21 E.
- the means 18 , 19 are illustrated as part of the master control device 16 , but could be separate devices.
- the means 18 , 19 may be implemented in software, hardware and/or firmware.
- converter stations and/or transmission lines should be provided with DC breakers able to break a fault current and quickly isolate a faulty cable line or converter from the rest of the DC transmission system 1 .
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Direct Current Feeding And Distribution (AREA)
- Supply And Distribution Of Alternating Current (AREA)
Abstract
Description
- The invention relates generally to the field of power transmission systems, and in particular to a multi-terminal DC power transmission system and to control thereof.
- A High Voltage Direct Current (HVDC) power transmission system is a viable alternative to alternating current (AC) power transmission systems, for example for long-distance distribution. Up to date, HVDC power transmission has been point-to-point two terminal power transmission with a few exceptions. A multi-terminal HVDC power transmission is more complex than the ordinary point-to-point power transmission. In particular, the control system is more elaborate and telecommunication requirements between stations become larger. A major reason for the more elaborate control system is difficulties to control the power flow within a large HVDC system, especially at disturbances.
- In case of disturbances within the HVDC power transmission network, for example outages of converters or lines, control actions have to be taken in order to ensure stability of the network and the power distribution. The aim of any such control actions is to handle the disturbances and provide a distribution of load that is acceptable and that enables uninterrupted power to be delivered to end users.
- Droop control is a well known method for handling disturbances. Such droop control is described in, for example, “Control of Multiterminal HVDC Transmission for Offshore Wind Energy”, T. Haileselassie et al. The document is mainly aimed at means for avoiding the need for communication when controlling the power distribution at a disturbance. Although functioning for load distribution at large disturbances such as loss of a converter, a drawback of the described droop control method is difficulties handling minor disturbances. In particular, even a rather small error in measurement will give great impact on the whole system.
- Further, the method described could operate acceptably for a star network configuration, but would encounter difficulties for other types of network configurations.
- In view of the above, there is a need for a solution that ensures proper control of multi-terminal DC power transmission systems during any type of disturbance as well as during steady state operation. Further, it would be desirable to provide such solution usable for any type of network configuration.
- It is an object of the invention to provide methods and means enabling an improved way of controlling a multi-terminal DC power transmission system, and in particular a control method and corresponding system that is well-functioning irrespective of type of disturbance.
- It is another object of the invention to provide a method and system practicable in any network configuration, in particular wherein converter stations of the DC multi-terminal transmission system may be interconnected and located in any suitable and desired way.
- These objects, among others, are achieved by a method for controlling power flow in a multi-terminal DC power transmission system and by a corresponding system as claimed in the appended independent claims.
- In accordance with the invention, a method for controlling power flow in a multi-terminal DC power transmission system is provided. The method comprises the first step of controlling the power flow to a steady state reference operating point for operating points within a control dead band defined for each respective converter station. The method further comprises the second step of controlling the power flow by means of droop control in at least one of the converter stations upon detection of exceeding of an end point of one or more of the control dead bands. By introducing a dead band within which steady state operation, including minor disturbances and regular load variations, is handled, the drawbacks of prior art are alleviated or at least mitigated. In particular, the use of dead bands renders the multi-terminal DC power transmission system less susceptible for errors in measurements. Further, by means of the invention, larger disturbances, for example failures resulting in islanded DC systems, as well as minor disturbances, can be handled. The invention thus provides a reliable and adaptable multi-terminal DC power transmission system. Further yet, the multi-terminal DC power transmission system in accordance with the invention can be utilized for any type of network configuration, including complex network configurations. The solution is thus suitable for all types of network configurations and this in turn provides a high flexibility when deciding converter station locations. In particular, owing to the introduced use of dead band in combination with droop control, there is no need for a common voltage reference during minor disturbances and mentioned problems of the prior art is overcome and any type of network configuration can be handled.
- In accordance with an embodiment of the invention the steady state reference operating points are related to a voltage profile of steady state operation of the multi-terminal DC transmission system and the control dead band are defined as steady state operation.
- In accordance with another embodiment of the invention, the droop characteristics for the droop control are defined individually for each converter station. Further, a particular converter station may have several different droop constants. The droop characteristics of the converter stations are one part for determining power sharing within the multi-terminal DC transmission system and the DC voltage at disturbances.
- In accordance with still another embodiment of the invention, each converter station is provided with limitations in power/current and overvoltages. Having break points in the droop characteristics ensures that the capability of any converter station or the capability of its connected AC network is not exceeded.
- In accordance with another embodiment of the invention the steady state reference operating point is determined by a master control unit of the multi-terminal DC power transmission system in consideration of DC voltage profile of the entire multi-terminal DC power transmission system. Transient and dynamic stability is ensured and the risks for interaction between power controls of different converter stations are thereby minimized.
- Further features, defined in further dependent claims, of the invention and advantages thereof will become evident when reading the following detailed description.
- The invention also relates to a corresponding multi-terminal DC power transmission system, whereby advantages similar to the above are achieved.
-
FIG. 1 illustrates an embodiment of a multi-terminal DC power transmission system in accordance with the present invention. -
FIG. 2 illustrates exemplary converter station characteristics. -
FIG. 3 illustrates a flow chart over steps included in a method in accordance with an embodiment of the invention. - It is initially noted that a multi-terminal DC power transmission system is conventionally understood to comprise a DC power transmission system comprising more than two converter stations. Although the invention is described in connection with the multi-terminal DC transmission system, it is realized that the present invention is also applicable to a DC transmission system comprising only two converter stations.
- The multi-terminal DC power transmission system is preferably a HVDC system, wherein HV may be defined to comprise any voltage level ranging for example from 300 kV, or even 80 kV. However, it is realized that the present invention is not restricted to any particular voltage levels or current levels, but is applicable to any such levels. Power transmission is understood to comprise transmission of electric power.
-
FIG. 1 illustrates an embodiment of a multi-terminal DC power transmission system 1 in accordance with the invention, in the following denoted DC transmission system in order of simplicity. The DC transmission system 1 comprises a number ofconverter stations FIG. 1 , it is realized that any number of converter stations can be included. - The
converter stations 10A, . . . , 10E in turn comprise inverters converting DC to AC, and/or rectifiers converting AC to DC. Other components and means conventionally used within a power network for enabling DC power transmission, but not forming part of the present invention, may also be included in theconverter stations 10A, . . . , 10E. - The
converter station 10A, . . . , 10E comprises anAC side AC network converter stations 10A, . . . , 10E further comprises aDC side converter stations 10A, . . . , 10E may be interconnected in any suitable manner, thereby constituting the DC transmission system 1. Eachconverter station 10A, . . . , 10E thus have anAC side 11A, . . . , 11E and aDC side 12A, . . . , 12E. - The
converter stations 10A, . . . , 10E may be interconnected by means of power transmission lines, also denoted cable lines, or by overhead lines in a known manner. Such power transmission lines allows the power transmission and are illustrated in theFIG. 1 byreference numerals - The DC transmission system 1 further comprises a
master control unit 16 responsible for coordination between theconverter stations 10A, . . . , 10E. More specifically, themaster control unit 16, also denoted grid master control, is arranged to coordinate the operation of the entire DC transmission system 1, and especially at disturbances and reconfigurations. These functions, as well as other control functions not mentioned, e.g. conventional control functions, may be implemented in software, hardware and/or firmware. Themaster control unit 16 may for example be a general purpose computer comprising appropriate software instructions enabling the desired control functions, for example able to send operating instructions to the converter stations. Examples of such control functions comprise receiving updated information regarding loading of all converter stations and especially the loading of a converter station pre-selected for DC voltage control; loading of all cable lines; DC voltages in all converter stations; limitations regarding voltage and current; desired dispatch for each converter station. Themaster control unit 16 may be located in one of the converter stations or located elsewhere in the DC transmission system 1. - Although the
master control unit 16 is the main tool for proper restoration of the operation after faults and disturbances, the DC transmission system 1 is nevertheless designed so as to function even in case of failure thereof and/or in case of slow response from themaster control unit 16. - Each converter station comprises a local control unit as well, for example enabling power regulation in the converter station.
- In this context it is also noted that a sub-grid of the entire grid, i.e. the DC transmission system 1, may have its own area master control. The
master control unit 16 then coordinates the area master controls for each area. - The
converter stations 10A, . . . , 10E are preferably connected to acommunication network 15, whereby data can be exchanged between the converter stations and whereby themaster control unit 16 is able to communicate with eachconverter station 10A, . . . , 10E. Thecommunication network 15 may for example be a telecommunication network or a wide area network such as the Internet or any combination of communication networks. - Briefly, in accordance with the present invention the type of control of the DC transmission system 1 is dependent on the prevailing conditions therein; during steady state and minor disturbances the
converter stations 10A, . . . 10E are arranged to work within a respective pre-defined dead band, while during large disturbances a droop control function is used. - Furthermore, limitation or break points are introduced in the droop characteristics for ensuring that neither any of the connected converter stations nor any of the connected AC networks are loaded beyond their respective individual capabilities.
- Steady state operation and operation during minor disturbances in accordance with the invention is described first in the following. Minor disturbances comprise for example normal load variations within the DC transmission system 1.
- During steady state, one of the
converter stations 10A, . . . , 10E of the DC transmission system 1 is arranged to be DC voltage controlled, striving to keep its DC voltage UDC constant. The DC voltage controlled converter station controls the DC voltage in such a way that all (or some) of the converter stations can take their part of the disturbance. The remaining converter stations are arranged to be power controlled, striving to keep their power P constant. - In the DC transmission system 1 only one converter station is in DC voltage control, which converter station may be pre-selected for DC voltage control. The other converter stations are pre-selected for power control, or are else in islanded network operation. A converter station in islanded network operation is disconnected from the DC transmission system 1 and is controlling both the frequency and the AC voltage, that is, the master control is not controlling the converter station.
- The converter station that is pre-selected for DC voltage control always operates in DC voltage control. This is in contrast to the converter stations pre-selected for power control, which operates in DC voltage control when disconnected from the DC transmission system 1. When the converter station pre-selected for power control is re-connected to the DC transmission system 1, it is transferred to power control.
- The converter station to be in DC voltage control may be suitably chosen, for example a converter station centrally located within the DC transmission system 1 and/or being connected to a relatively stable and strong ac-network. The connected ac network of the chosen converter station should have the capability to temporarily take the balance power variation due to load variations in converter stations operating in islanded network operation, in frequency control, in power oscillation damping etc. The chosen converter station should be close to the electrical central point and the DC voltage should be close to the median DC voltage of the DC transmission system 1. However, the choice of converter station in DC voltage control may be selected in any other suitable way.
- Each converter station in power control controls its AC side power to a reference value, a steady state reference operating point, provided that the dc-voltage is within acceptable limits. The limits of a converter station are described more in detail later. Only converter stations in normal power control can control their power and the converter station in DC voltage control has to take the balance. The power of converter stations in power control can be controlled in any suitable manner, for example by means of conventional PI regulation, performed by the local control unit.
- It is noted that for the DC transmission system 1, a converter station set in power control mode may be placed on equality with current control mode, as the power is nearly linear with the current.
- In order to ensure transient and dynamic stability and for minimizing the risks for interaction between power controls of different converter stations, the DC voltage in a central point of the system is fixed in a short term. Otherwise, power changes in any converter station will result in voltage variation in all other converter stations, which is to be counteracted by the power control in those converter stations. The set point for the DC voltage reference for the converter station in DC voltage control is defined by the
master control unit 16, set in view of the DC voltage profile of the complete DC transmission system 1. - Transiently and dynamically the converter station pre-selected for DC voltage control controls its voltage to the above short-term fixed reference within a defined power range for normal operation, i.e. within a control dead band for the voltage controlled converter station. The remaining converter stations, i.e. the converter stations pre-selected for power control, control their ac side power to the desired order value as long as the DC voltage is within a defined voltage range for normal operation, i.e. within a control dead band for the power controlled converter stations. Outside the defined voltage/power range for normal steady state operation, the converter station has a voltage/power droop characteristic, which is described more in detail later in the description. The normal steady state operation also includes minor disturbances, for example normal load variations of the DC transmission network 1.
- The power, current and voltage limits of a converter station are normally defined by local conditions. Such local conditions are communicated to the
master control unit 16 from eachconverter station master control unit 16 defines a number of settings: -
- The DC voltage reference set point for the converter station in DC voltage control,
- The power order for the converter stations in power control,
- The dead band in power and DC voltage, respectively, before activating the droop characteristics, the dead bands being determined individually for each converter station,
- The droop constant(s) for each individual converter station,
- The operating limits of each converter, i.e. limitations regarding voltage and current.
- With reference now to
FIG. 2 , an example ofcharacteristics converter stations 10A, . . . , 10E, respectively, connected to the DC transmission system 1 is illustrated. - For each converter station, a dead band is defined in accordance with the above described. The dead bands are indicated in the
FIG. 2 atreference numerals respective converter stations - The small squares indicate the steady state operating points 22A, 22B, 22C, 22D, 22E of the respective converter stations. Each respective steady
state operating point Converter station 10B is pre-selected for DC voltage control while theother converter stations - As long as the operating point of a converter station is within its defined dead band, the converter station controls its voltage or power to the short-term fixed reference. In particular, the
converter station 10B pre-selected for voltage control controls its voltage to the short-term fixed reference within itsdead band 21A. Theconverter station 10B has a powerdead band 21A, within which the power is allowed to vary and still be considered to be within normal operation. Theconverter stations dead bands - The sloping part of the characteristics of
FIG. 2 illustrates droop characteristics of the converter stations. It is noted that a converter station may have one or several different droop characteristics. It can be seen from theFIG. 2 , thatconverter station 10A, for example, has three different droop constants, whileconverter station 10B has two different droop constants andconverter station 10C has a single droop constant. - As mentioned earlier, there are set power/current and overvoltage limits for each converter station. In
FIG. 2 such limits are also illustrated. The power/current limitations of the converter stations combined with the power limitations of its connected AC network are shown as vertical lines. The horizontal lines at +10 kV represent maximum allowed DC voltage for operation, i.e. an exemplary rated voltage forconverter stations - As an example, the
converter station 10B, that is pre-selected for DC voltage control, will take the power imbalance within itsdead band 21B in power. The combined characteristics forconverter station 10B shown inFIG. 2 prevents that the converter station in DC voltage control is overloaded. The converter station control will prevent that the inverter is overloaded. It is the duty of themaster control unit 16 to define the parameters of the converter station characteristics in such a way that the DC voltage is kept within the desired and set range even at equipment outages and other types of disturbances. - It is noted that the
master control unit 16 may order more stringent limitations than the limitations set based on local conditions. - The converter station characteristics, i.e. the dead bands, the droop constants, and sometimes even the converter station limits, may have to be adapted to some degree. The characteristics may for example have to be adapted to the actual power flow of the DC transmission system 1. Thus, at a significant change of the DC transmission system 1 power flow or of the conditions of the connected
AC networks 13A, . . . , 13E, the parameters of the converter station characteristics has to be recalculated by themaster control unit 16 and transmitted to theconverter stations -
FIG. 2 thus illustrates the inventive idea of dead band droop control of DC voltage versus power for fiveconverter stations 10A, . . . , 10E connected to the DC transmission system 1. - In case of larger disturbances, such as tripping of a cable line or outage of a converter station, droop control is activated. In particular, when the prevailing conditions of a particular converter station results in that the end points of the dead bands for that particular converter station are exceeded, the control of at least that particular converter station is changed to droop control. That is, if the operating point falls outside the end points of the dead band, then droop control is activated.
- In the droop control, any conventional droop control method may be used. For example, one droop control method is to operate all converter stations in the DC transmission system in DC voltage control with a voltage reference that is dependent on the power level, that is
-
U ref =U refn0−droop(P DC −P DCref) - The characteristic is a constant DC voltage in series with a resistance and it is stable and works well for taking care of power variations as well as an outage.
- An improved way of obtaining a common voltage reference is subject for a co-pending patent application, entitled “A method for controlling power flow within a DC power transmission network, control device and computer program product” and filed on even day with the present application. In short, the method comprises the step of controlling the power flow to a set operating point by using a common feedback signal, Ud,common=Ud ref+D*(PPCC−PPCC ref), wherein Ud ref is a reference voltage set to be same for all converter stations, D is a droop constant, PPCC is active power injected into an AC network connected to the converter stations and PPCC ref is a set reference power. The feedback signal is common to all of the converter stations and based on an overall voltage level in the DC transmission power network. The common feedback signal results in a highly improved reference tracking of set-points; it can be shown that each converter station tracks its power reference perfectly. An accurate load sharing in the DC grid during disturbances is accomplished and also accurate steady-state operation. The present invention may utilize such power flow control method.
-
FIG. 3 illustrates a flow chart over steps of a method in accordance with the invention for controlling power flow within the multi-terminal DC power transmission system 1 comprising two ormore converter stations method 30 comprises the first step of controlling 31 the power flow to a steady statereference operating point dead band respective converter station - The control dead band comprises the earlier described power/voltage dead bands. That is, a power dead band for a voltage controlled converter station and a voltage dead band for a power controlled converter station.
- The
method 30 comprises the second step of controlling 32 the power flow by means of droop control in at least one of theconverter stations dead bands - The steady state
reference operating point dead bands reference operating point master control unit 16 in consideration of DC voltage profile of the entire multi-terminal DC power transmission system 1. - In an embodiment, the control
dead bands converter station - In another embodiment, the control dead band of a
converter station converter stations 10B has a powerdead band 21B, while the remainingconverter stations dead bands - In yet another embodiment, the droop characteristics for the droop control are defined individually for each
converter station - In another embodiment, limitations in power/current and overvoltages are defined for each
converter station - The invention also encompasses the multi-terminal DC power transmission system 1 comprising two or
more converter stations reference operating point dead band respective converter station FIG. 1 the multi-terminal DC power transmission system 1 further comprises means 18 for controlling the power flow by means of droop control in at least one of theconverter stations dead bands converter stations dead bands master control device 16, but could be separate devices. The means 18, 19 may be implemented in software, hardware and/or firmware. - It is noted that in order for the invention to be applicable for islanded DC systems, converter stations and/or transmission lines should be provided with DC breakers able to break a fault current and quickly isolate a faulty cable line or converter from the rest of the DC transmission system 1.
Claims (20)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
PCT/EP2010/059308 WO2012000548A1 (en) | 2010-06-30 | 2010-06-30 | A multi-terminal dc transmission system and method and means for control thereof |
Publications (2)
Publication Number | Publication Date |
---|---|
US20130334887A1 true US20130334887A1 (en) | 2013-12-19 |
US8736112B2 US8736112B2 (en) | 2014-05-27 |
Family
ID=43611118
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/807,650 Expired - Fee Related US8736112B2 (en) | 2010-06-30 | 2010-06-30 | Multi-terminal DC transmission system and method and means for control there-of |
Country Status (4)
Country | Link |
---|---|
US (1) | US8736112B2 (en) |
EP (1) | EP2589127B1 (en) |
CN (1) | CN102986110B (en) |
WO (1) | WO2012000548A1 (en) |
Cited By (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20150131342A1 (en) * | 2012-07-17 | 2015-05-14 | Abb Research Ltd | Multi terminal hvdc control |
US20160268818A1 (en) * | 2015-03-10 | 2016-09-15 | Lsis Co., Ltd. | Electricity providing system including battery energy storage system |
CN106684896A (en) * | 2017-02-08 | 2017-05-17 | 武汉船用电力推进装置研究所(中国船舶重工集团公司第七二研究所) | Three phase four wire system ship power grid power management system and method |
CN106911131A (en) * | 2015-12-22 | 2017-06-30 | 国网智能电网研究院 | A kind of em ergency power support control method of AC network subregion interconnect device |
US20170207630A1 (en) * | 2013-02-26 | 2017-07-20 | Nr Electric Co., Ltd | Method for incorporating non-operating station into operating system in multi-terminal flexible dc transmission system |
CN107404119A (en) * | 2017-06-14 | 2017-11-28 | 国家电网公司 | A kind of electric automobile load turns the control method for system |
US20180262007A1 (en) * | 2015-09-18 | 2018-09-13 | Abb Schweiz Ag | Micro-grid having a diesel generator with clutch |
CN109120005A (en) * | 2018-06-22 | 2019-01-01 | 华北电力大学(保定) | A kind of Multi-end flexible direct current transmission system power coordination control method |
CN109742784A (en) * | 2018-12-18 | 2019-05-10 | 国家电网有限公司 | A kind of bulk power grid large capacity fast electric air braking system control method |
JP2019208337A (en) * | 2018-05-30 | 2019-12-05 | 三菱電機株式会社 | Control device for dc converter |
CN110797902A (en) * | 2019-11-29 | 2020-02-14 | 国网天津市电力公司电力科学研究院 | Improved master-slave control method for direct-current power distribution network |
CN113489044A (en) * | 2021-07-12 | 2021-10-08 | 国网新疆电力有限公司营销服务中心(资金集约中心、计量中心) | Multi-terminal flexible direct current transmission self-adaptive droop control method considering line resistance |
EP3711134B1 (en) | 2017-11-14 | 2022-01-05 | Hitachi Energy Switzerland AG | Voltage droop-based method in a power transmission system |
EP3070827B1 (en) * | 2015-03-16 | 2022-09-07 | General Electric Technology GmbH | Start-up of hvdc networks |
Families Citing this family (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2013152482A1 (en) * | 2012-04-11 | 2013-10-17 | Abb Technology Ltd. | Master control method for a series mtdc system and element thereof |
CN102969733B (en) | 2012-11-08 | 2014-12-03 | 南京南瑞继保电气有限公司 | Coordination control method of multiterminal flexible direct current power transmission system |
CN104518519B (en) * | 2013-09-26 | 2017-11-03 | 南京南瑞继保电气有限公司 | DC voltage control method and device |
WO2015049005A1 (en) * | 2013-10-03 | 2015-04-09 | Abb Technology Ltd | Method and apparatus for damping oscillations in a power system |
EP2897245B1 (en) * | 2014-01-17 | 2017-07-26 | General Electric Technology GmbH | Multi-terminal DC electrical network |
ES2739680T3 (en) * | 2014-03-18 | 2020-02-03 | Siemens Ag | Voltage regulation in multiterminal HVDC network |
CN104184139B (en) * | 2014-09-12 | 2016-03-30 | 东南大学 | For DC power flow controller and the control method of Multi-end flexible direct current transmission system |
CN105896517B (en) * | 2014-12-31 | 2018-08-28 | 国家电网公司 | A kind of voltage droop control method of DC grid |
CN104505847B (en) * | 2014-12-31 | 2016-09-14 | 上海电力学院 | A kind of microgrid droop control optimization method controlled based on sliding formwork |
US10008854B2 (en) | 2015-02-19 | 2018-06-26 | Enphase Energy, Inc. | Method and apparatus for time-domain droop control with integrated phasor current control |
GB2537684A (en) * | 2015-04-24 | 2016-10-26 | Alstom Technology Ltd | Controller |
EP3392994B1 (en) | 2017-04-19 | 2020-09-16 | Siemens Aktiengesellschaft | Method for load flow regulation within a direct current network |
EP3652850A2 (en) | 2017-07-10 | 2020-05-20 | ABB Schweiz AG | Variable power charging |
US10658845B2 (en) * | 2017-12-11 | 2020-05-19 | Ge Energy Power Conversion Technology Limited | Method and system for droop control of power systems |
CN108574309B (en) * | 2018-04-24 | 2021-04-27 | 华北电力大学(保定) | Difference-free direct-current voltage droop control method suitable for alternating-current and direct-current hybrid micro-grid |
CN109038636B (en) * | 2018-08-06 | 2021-06-04 | 国家电网公司华东分部 | Data-driven direct-current receiving-end power grid dynamic reactive power reserve demand evaluation method |
CN109390966A (en) * | 2018-12-25 | 2019-02-26 | 四川大学 | A kind of more direct current control method for coordinating based on singular value decomposition |
CN110198045B (en) * | 2019-05-17 | 2022-11-18 | 华北电力大学(保定) | VSC-MTDC additional frequency adaptive droop control method |
FR3098037B1 (en) * | 2019-06-26 | 2021-06-18 | Inst Supergrid | Control method of an electrical transmission network |
CN110808605B (en) * | 2019-11-20 | 2021-02-09 | 天津大学 | Dynamic stability analysis method for current mode droop control multi-terminal direct current system |
Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP1467463A1 (en) * | 2003-04-09 | 2004-10-13 | General Electric Company | Wind farm and method for operating same |
US20050040655A1 (en) * | 2003-08-18 | 2005-02-24 | Wilkins Thomas A. | Continuous reactive power support for wind turbine generators |
US6891281B2 (en) * | 2000-05-11 | 2005-05-10 | Aloys Wobben | Method for operating a wind power station and wind power station |
US20080111380A1 (en) * | 2005-11-29 | 2008-05-15 | General Electric Company | System And Method For Utility and Wind Turbine Control |
US7800242B2 (en) * | 2006-10-19 | 2010-09-21 | Siemens Aktiengesellschaft | Wind energy installation and method of controlling the output power from a wind energy installation |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CA1279678C (en) | 1986-02-18 | 1991-01-29 | James P. Karlen | Industrial robot with servo |
JP2585425B2 (en) | 1989-05-10 | 1997-02-26 | 株式会社日立製作所 | Vertical articulated robot |
JPH10175188A (en) | 1996-12-17 | 1998-06-30 | Fanuc Ltd | Robot structure |
US7511385B2 (en) | 2005-11-11 | 2009-03-31 | Converteam Ltd | Power converters |
GB0523087D0 (en) * | 2005-11-11 | 2005-12-21 | Alstom Power Conversion Ltd | Power converters |
JP2007229874A (en) | 2006-03-01 | 2007-09-13 | Kawasaki Heavy Ind Ltd | Industrial robot |
US8760888B2 (en) | 2006-06-30 | 2014-06-24 | Abb Technology Ag | HVDC system and method to control a voltage source converter in a HVDC system |
US7839024B2 (en) | 2008-07-29 | 2010-11-23 | General Electric Company | Intra-area master reactive controller for tightly coupled windfarms |
-
2010
- 2010-06-30 WO PCT/EP2010/059308 patent/WO2012000548A1/en active Application Filing
- 2010-06-30 EP EP20100725809 patent/EP2589127B1/en not_active Revoked
- 2010-06-30 US US13/807,650 patent/US8736112B2/en not_active Expired - Fee Related
- 2010-06-30 CN CN201080067859.4A patent/CN102986110B/en active Active
Patent Citations (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6891281B2 (en) * | 2000-05-11 | 2005-05-10 | Aloys Wobben | Method for operating a wind power station and wind power station |
EP1467463A1 (en) * | 2003-04-09 | 2004-10-13 | General Electric Company | Wind farm and method for operating same |
US20050040655A1 (en) * | 2003-08-18 | 2005-02-24 | Wilkins Thomas A. | Continuous reactive power support for wind turbine generators |
US20080111380A1 (en) * | 2005-11-29 | 2008-05-15 | General Electric Company | System And Method For Utility and Wind Turbine Control |
US7800242B2 (en) * | 2006-10-19 | 2010-09-21 | Siemens Aktiengesellschaft | Wind energy installation and method of controlling the output power from a wind energy installation |
Non-Patent Citations (2)
Title |
---|
"Voltage Conrol Method using Modified Voltage Droop COntrol in LV Distribution System", Seo et al. IEEE T&D Asia 2009. * |
"Wireless parallel operation of high voltage DC power supply using steady-state estimatiuon", Baek et al., IEEE 0-7803-8730-9/04. Copyright IEEE 2004. * |
Cited By (20)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US9601926B2 (en) * | 2012-07-17 | 2017-03-21 | Abb Research Ltd | Multi terminal HVDC control |
US20150131342A1 (en) * | 2012-07-17 | 2015-05-14 | Abb Research Ltd | Multi terminal hvdc control |
US10283965B2 (en) * | 2013-02-26 | 2019-05-07 | Nr Electric Co., Ltd | Method for incorporating non-operating station into operating system in multi-terminal flexible DC transmission system |
US20170207630A1 (en) * | 2013-02-26 | 2017-07-20 | Nr Electric Co., Ltd | Method for incorporating non-operating station into operating system in multi-terminal flexible dc transmission system |
US10090685B2 (en) * | 2015-03-10 | 2018-10-02 | Lsis Co., Ltd. | Electricity providing system including battery energy storage system |
US20160268818A1 (en) * | 2015-03-10 | 2016-09-15 | Lsis Co., Ltd. | Electricity providing system including battery energy storage system |
EP3070827B1 (en) * | 2015-03-16 | 2022-09-07 | General Electric Technology GmbH | Start-up of hvdc networks |
EP4125203A1 (en) * | 2015-03-16 | 2023-02-01 | General Electric Technology GmbH | Start-up of hvdc networks |
US10673239B2 (en) * | 2015-09-18 | 2020-06-02 | Abb Power Grids Switzerland Ag | Micro-grid having a diesel generator with clutch |
US20180262007A1 (en) * | 2015-09-18 | 2018-09-13 | Abb Schweiz Ag | Micro-grid having a diesel generator with clutch |
CN106911131A (en) * | 2015-12-22 | 2017-06-30 | 国网智能电网研究院 | A kind of em ergency power support control method of AC network subregion interconnect device |
CN106684896A (en) * | 2017-02-08 | 2017-05-17 | 武汉船用电力推进装置研究所(中国船舶重工集团公司第七二研究所) | Three phase four wire system ship power grid power management system and method |
CN107404119A (en) * | 2017-06-14 | 2017-11-28 | 国家电网公司 | A kind of electric automobile load turns the control method for system |
EP3711134B1 (en) | 2017-11-14 | 2022-01-05 | Hitachi Energy Switzerland AG | Voltage droop-based method in a power transmission system |
JP2019208337A (en) * | 2018-05-30 | 2019-12-05 | 三菱電機株式会社 | Control device for dc converter |
JP7006509B2 (en) | 2018-05-30 | 2022-01-24 | 三菱電機株式会社 | DC converter control device |
CN109120005A (en) * | 2018-06-22 | 2019-01-01 | 华北电力大学(保定) | A kind of Multi-end flexible direct current transmission system power coordination control method |
CN109742784A (en) * | 2018-12-18 | 2019-05-10 | 国家电网有限公司 | A kind of bulk power grid large capacity fast electric air braking system control method |
CN110797902A (en) * | 2019-11-29 | 2020-02-14 | 国网天津市电力公司电力科学研究院 | Improved master-slave control method for direct-current power distribution network |
CN113489044A (en) * | 2021-07-12 | 2021-10-08 | 国网新疆电力有限公司营销服务中心(资金集约中心、计量中心) | Multi-terminal flexible direct current transmission self-adaptive droop control method considering line resistance |
Also Published As
Publication number | Publication date |
---|---|
EP2589127A1 (en) | 2013-05-08 |
WO2012000548A1 (en) | 2012-01-05 |
EP2589127B1 (en) | 2014-06-25 |
CN102986110A (en) | 2013-03-20 |
CN102986110B (en) | 2016-02-17 |
US8736112B2 (en) | 2014-05-27 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US8736112B2 (en) | Multi-terminal DC transmission system and method and means for control there-of | |
US8946917B2 (en) | Method for controlling power flow within a wind park system, controller, computer program and computer program products | |
US10305291B2 (en) | Voltage source convertors | |
EP2589128B2 (en) | Method and control device for controlling power flow within a dc power transmission network | |
US20080252142A1 (en) | Apparatus for Electrical Power Transmission | |
US10615711B2 (en) | Apparatus for controlling output voltage for single-type converter, and method therefor | |
US20080205093A1 (en) | Apparatus for Electrical Power Transmission | |
Gwon et al. | Mitigation of voltage unbalance by using static load transfer switch in bipolar low voltage DC distribution system | |
CN107431360B (en) | Power transmission network | |
KR20120030556A (en) | Controlling an inverter device of a high voltage dc system for supporting an ac system | |
CN106063102B (en) | Voltage source converter | |
JPWO2017163508A1 (en) | Power converter | |
JP5948116B2 (en) | Uninterruptible power supply system | |
US10097008B2 (en) | Power network system and control method thereof, computer readable media, power router and management server | |
CN109802417A (en) | Reply DC Line Fault impacts the power grid emergency control method and device of weak communication channel | |
US10476269B2 (en) | Method for independent real and reactive power flow control using locally available parameters | |
Xu et al. | MTDC systems for frequency support base on DC voltage manipulation | |
US10778011B2 (en) | Power transmission networks | |
Neumann et al. | Response of an AC-DC hybrid transmission system to faults in the AC network | |
JP2020137299A (en) | Electric power system stabilization system | |
JP2016101030A (en) | Power transmission system and control method therefor | |
US20240088673A1 (en) | Electric power control system | |
US20220360161A1 (en) | Electrical assembly | |
JP2018081563A (en) | Power conversion device and control method thereof, and power supply system | |
US20190267909A1 (en) | Energy distribution apparatus, system and method thereof |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: ABB TECHNOLOGY AG, SWITZERLAND Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:LINDEN, KERSTIN;FLISBERG, GUNNAR;JUHLIN, LARS-ERIK;AND OTHERS;SIGNING DATES FROM 20121218 TO 20130121;REEL/FRAME:029705/0929 |
|
FEPP | Fee payment procedure |
Free format text: PAYOR NUMBER ASSIGNED (ORIGINAL EVENT CODE: ASPN); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
STCF | Information on status: patent grant |
Free format text: PATENTED CASE |
|
AS | Assignment |
Owner name: ABB SCHWEIZ AG, SWITZERLAND Free format text: MERGER;ASSIGNOR:ABB TECHNOLOGY LTD.;REEL/FRAME:040622/0040 Effective date: 20160509 |
|
MAFP | Maintenance fee payment |
Free format text: PAYMENT OF MAINTENANCE FEE, 4TH YEAR, LARGE ENTITY (ORIGINAL EVENT CODE: M1551) Year of fee payment: 4 |
|
AS | Assignment |
Owner name: ABB POWER GRIDS SWITZERLAND AG, SWITZERLAND Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:ABB SCHWEIZ AG;REEL/FRAME:052916/0001 Effective date: 20191025 |
|
FEPP | Fee payment procedure |
Free format text: MAINTENANCE FEE REMINDER MAILED (ORIGINAL EVENT CODE: REM.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
LAPS | Lapse for failure to pay maintenance fees |
Free format text: PATENT EXPIRED FOR FAILURE TO PAY MAINTENANCE FEES (ORIGINAL EVENT CODE: EXP.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY |
|
STCH | Information on status: patent discontinuation |
Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362 |
|
FP | Lapsed due to failure to pay maintenance fee |
Effective date: 20220527 |